Dry rectifier



y 21, 1935- w. c. VAN GEEL ET AL 2,002,221

DRY RECTIFIER Filed May 1, 195].

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Patented May 21, 1935 UNITED STATES PATENT OFFICE mens, Eindhoven, Netherlands, N. V. Philips Gloeilampenfabrieken,

hoven, Netherlands assignors. to

Find- Application May 1, 1931,,Serial No. 534,358 In the Netherlands May 15, 1930 10 Claims. (Cl- 175-388) This invention has reference to a dry rectifier each cell of which is constituted by two substances of different electron emissive power separated by a nonconductive intermediate layer.

In the case of the well known rectifiers having a nonconductive intermediate layer, this layer is formed by chemical agency or otherwise from substances of which the adjoining outside layers are made.

The invention is characterized in that the intermediate layer is formed independently of the material of the two outside layers. It has been found that thus a particularly satisfactory rectifying action is obtained and that such rectifiers can be manufactured more simply and cheaply than the-well known rectifiers of this type.

The use of a layer formed independently of the material of the two, outside layers is known per se but hitherto the intermediate layer was constituted. by a conductor or a semi-conductor. It has, however, been found that quite satisfactory results are only obtained when the intermediate layer is nonconductive. V

In contradistinction to the common practice, the intermediate layer is preferably made of a substance which does not form part per se or as a compound of the substances that constitute the two outside layers.

In one form of construction of the intermediate layer, thelatter consists of a plate or strip of artificial resin, (for example of Bakelite), lacquer, collodium, silicious varnish or the like. 1

A simple method of manufacturing a rectifier according to the invention is by spraying the intermediate layer on either one of the two adjoining layers but other methods of manufacturing are also possible. .Lacquer, for example,

may be coated in a very thin layer on one ofthe' outside layers. In a preferred embodiment the intermediate layer is sprayed on a plate or strip which constitutes one of the outside layers and after that the second outside layer is sprayed on the intermediate layer. Thus a very compact rectifier is obtained in a very simple manner. When suitable materials are chosen, a rectifier consisting of a great number of cells may be built up entirely by successively spraying on each other a plurality of different layers in the manner indicated.

In this case a metal of good emissive power is first sprayed on a solid substratum and upon this layer is sprayed an insulating layer upon which in its turn is sprayed a layer of a substance of low emissive power and upon this layer is sprayed a layer of the metal initially used, and so on.

Thus any numberof cells can be combined 5 and arranged at will in series or in parallel by bringing out from the individual cells or group of cells the required connecting wires.

In order that the invention may be clearly understood and readily carried into effect, it will 10 be more'fully described in connection with the accompanying drawing in which the single figure is a sectionized view of a cell of a rectifier in accordance with the invention.

Referring to the figure, the cell shown therein consists of a copper plate I which has sprayed on it or is coated with a layer 2 of bakelite, and a plate 3 of compressed CuaS which is arranged so as to lie in contact with the latter. Although a very simple. circuit arrangement is shown, it is,

,of course, obvious that the cells described can be built up in a variety of ways and be used in different circuit arrangements for rectifying alternating current.

For combining various cells of a rectifier; all 26 the plates or layers may be, for example, centrally apertured and a bolt inserted through these apertures, this bolt also passing through two clamping plates provided on the two ends of the rectifiers. By tightening a nut provided at one 30 end of the bolt the clamping plates force the cells against each other and a good electric and mechanical connection between same is established. For the cathode, use may be made not only of the copper mentioned before but also of a great many other substances, for example, zirconium, titanium, hafnium, thorium. Similarly for the anode a great many difierent materials may be used, for example, copper iodide which has added to it free iodine lead sulphide, molybdenum 5111- phide, tungsten sulphide, iron sulphide, iron hafnium, manganese oxide, silver chloride with free iodine, lead dioxide, cadmium oxide.

It is also obvious that for the constitution of the intermediate layer various substances other than those mentioned before may be used. In general, any non-conductor which is adapted to be applied in a thin layer is suitable. Obviously, those nonconductors will, preferably be used which are adapted to be spread or squirted in the form of a thin layer and which layer at the same time is non-porous and has sufiicient resistance to mechanical and atmospherical influences.

1 What we claim is:

independently oi! two layers or substances having difierent electr emissivities, and a very thin non-conductive solid layer interposed-between the first-mentioned layers, said solid layer being substantially cold and non-ionized during the operation or the rectifier, said intermediate layer being formed the substance of the outside layers.

2. Adry rectifier cell having asymmetrical conductivity when cold and comprising two outside layers formed of substances having diiIerent electron emissivities, and a very thin intermediate layer of a non-conductive substance, said intermediate layer being formed independently of the substances of the two outside layers and-being substantially cold during'the operation of the cell.

3. A dry rectifier cell consisting'of two layers of substances having difierent electron emissivities, and an interposed thin layer consisting-oi an insulating material such as artificial resin, lacquer, collodion, silicious varnish or the like, said material being substantially cold and non-ionized during the operation of the cell.

4. A dry rectifier cell comprising two layers substances having different electron emissivities,

and one very thin interposed'layer of an insulating material sprayed on one 01' said outside layers, said material remaining substantially cold during the operation of the cell.

5. A dry rectifier cell comprising two outside layers or substances having different electron emissivities, and a very thin interposed layer having high insulating properties and being sprayed on one of the said outside layers and formed independently of the substance of the outside layers, said interposed layer being substantially cold during the operation of the cell.

6. A dry rectifier cell comprising two' outside layers 01' substancesjhaving diilerent electron emissivities, and a very thin intermediate layer sprayed on one of said outside layers, said intermediate layer remaining substantially cold during the operation of the cell and being of a compound, the positive part of which differs from the material of the two outside layers.

7. A dry rectifier comprisinga conducting layer, a very thin insulating layer sprayed on said conducting layer, and a second conducting layer sprayed on said insulating layer, said conducting layers having different electron emissivities and said insulating layer remaining substantially cold during the operation of the rectifier and consisting of a compound, the positive part of which cold and non-ionized during the operation of the rectifier.

10. A dry rectifier, comprising two outside layers formed of conductive substances having different electron emissivities, and an intermediate layer of a substance of a colloidal varnish nature.

WILLEM CHRISTIAAN VAN GEEL. HENDRIK EMMENS.

'pheric influence, said material being substantially 

